Treatment of tar



EDMUND O. RHODES AND FLOYD D. HAG-ER, OF PITTSBURGH, PENNSYLVANIA, ,AS-

oil

Patented Apr. 25, 1933 UNITED STATES PATENT oFFicE SIGNORS TO THE AMERICAN TAR ZE'RODU'CTS COMPANY, A CORPORATION OF DELA- WARE No Zbrawing.

This invention relates to processes of treating tar and to products resulting from such treatment.

vAn object of the present invention is to provide a method of separating tar into various fractions and to produce thereby various useful products.

In accordance with the present invention, solvents such as aliphatic ketones and mixtures of aliphatic ketones and alcohols are thoroughly mixed with tar. The mixture is permitted to settle and there results a layer of constituents insoluble in the above solvents,

and a layer comprising, a. solution of constituents soluble in the solvents mentioned.

. The insoluble material is generally in a finely divided state. It is apitch-like. product relatively rich in ben'zol-insoluble constituents and can be readily coked.

The soluble material is separated from the solvent by distillation. After the solvent is distilled off, a creosote-like product is obtained which is relatively rich in high-boiling constituents and is useful for the same general purposes for which creosote is used. The soluble portion may be treated to obtain pitches having a wide range of melting points. By distilling the soluble portion with or without the addition of steam or by steam alone a creosote-like distillate and a pitch residue may be obtained. When pitches of high melting points are desired, 7

it is preferable to carry out the distillation with steam. The pitch residue is characterized by its remarkable degree of homogeneity, luster and comparatively low content of benzol-insoluble material.

The form and character of the materials extracted from the tar may be varied considerably by changing the composition of the solvent and/or the temperature at which the extraction is conducted. In other words, the solvent and the temperature of extraction may be selected to obtain the particular fraction desired. The resulting products vary per. molecule.

.TBEATMEN'J. or ran Application filed January 2, 1930. SerialNo. 418,151.

with the ketone used, or with the ketone. and alcohol mixture or with the ketone-alcohol ratio. 7V

It is preferable to use alcohols and ketones of low molecular weight as, for instance, those having not more than six carbon atoms Ketones such as dimethyl ketone, methylethyl ketone and diethyl ketone, and alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol may be used.

,The .followingexamples are given byway of illustration: p H

EwampZeJ.-Ten parts by volumeof ace tone are mixed with onepart by volume of crude coke-oven tar. The mixture is permitted to stand'unt-il the insoluble portions settle to the bottom of the container in which the materials are mixed. The liquid portion Per cent To 210 C l .4- 210235 4.7 235-270 9.5 270-315 9.5 315855 13.3 Residue 60.0

The residue obtained by the above distillation as well as the insoluble portion of the tar may be sold for use as such or it may be coked.

Example 2.One part by volume of tar is thoroughly mixed with ten parts by volume of a 1: 1 mixture of acetone and methyl alcohol. The soluble portion of the tar is-separated from the insoluble portion as indicated in Example 1. The proportion of the soluble constituents is found to be about 69% of the original tar.

The following yields are obtained by distilling the soluble portion The residue obtained by the above distillation as well as the insoluble portion of the tar may be used as such or it may be coked.

Example 3.One part by volume of tar is mixed with approximately five parts by volume of acetone. The soluble portion is about 87% of the original tar. By steam-distilling the soluble portion at approximately 300 C. residues having various melting points may be obtained. For example, a high melting residue (180 C.) so prepared has a pitchy nature and an unusually high luster vfor a J pitch of so high a melting point. Its free carbon content is about 20%, which is considere'd low in view of its melting point. When the said residue is coked, a very desirable product is obtained.

The distillate obtained by the above steam distillation may be again distilled. The following yields are obtained:

- Peicent To 210 C 210-235 7.1 235270 14.5 270-315 12.8 315-355; 16.1 Residue 47.4

* means of the solvents mentioned above is found to be an excellent substitute for creo-' sote. Itis practically free from suspended particles visible up to 1,000X magnification. The viscosity of the dry material is far less than that of dry creosoting tar, especially at creosoting temperature. For example, the viscosity, of the dry extracted material at 85 C. and at 100 C. is about 48 sec/100 c.c. and 39 sec/100 0.0. respectively, and the viscosity of the corresponding dry creosoting tar at 85 C. and at 100 C. is about 92 sec/100 cc. and 60 sec/100 0.0. respectively, as measured by the Engler viscosimeter.

The pitches prepared from the soluble portion in the above manner have a particularly high luster and yield a high quality coke. They also have a very low content of benzol-in'soluble material as compared with pitches having the same melting point when prepared by usual methods.

We claim as our invention:

1. A process comprising treating hightemperature coke oven tar with a solvent containing acetone to extract the soluble matter from the said tar, distilling the solution thus formed to remove the said solvent, and distilling the soluble matter to produce a creosote-like distillate and a pitch-like residue.

2. A tar fraction obtained from hightemperature coke oven tar by extracting the said fraction from the tar with a liquid solvent containing acetone and alcohol and removing the said solvent.

3. A composition of matter comprising a pitch-like substance which is the insoluble portion of high-temperature coke oven tar treated with a solvent containing acetone and alcohol.

4..A process of fractionally separating products from high-temperature coke oven tar by meansof solvents including alcohol and ketone, and varying the proportions of separated products by varying the particular ketone and alcohol, and by varying the proportions of ketone and alcohol in the solvent, which process comprises preparing a solvent from alcohol and ketone selected to obtain a desired soluble and insoluble por tion of the tar, treating the said tar with the resulting solvent to extract the soluble matter from the said tar, separating the resulting solution from the undissolved portion of the said tar, and distilling the solution to obtain the soluble portion ofthe said tar.

In testimony whereof, we have hereunto subscribed our names this 31st day of December, 1929.

EDMUND O. RHODES.

FLOYD D. HAGER. 

